Wij zitten naast elkaar in de trein.

Both wij and we mean we.

• we is the more common everyday form in speech.
• wij is a slightly fuller, more stressed form.
• wij is often used for emphasis, contrast, or a more careful/written style.

So Wij zitten naast elkaar in de trein and We zitten naast elkaar in de trein are both correct. In normal conversation, we zitten... is probably more common.

Dutch often uses so-called posture verbs where English simply uses to be.

The main ones are:

• zitten = to sit / to be seated
• staan = to stand
• liggen = to lie
• zijn = to be

In Dutch, if people are physically sitting somewhere, zitten is very natural. Since the sentence is about being in a train and next to each other, Dutch prefers zitten if the people are seated.

So:

• Wij zitten naast elkaar in de trein = natural if you are sitting there
• Wij zijn naast elkaar in de trein = much less natural in this situation

English says We are sitting next to each other on the train or even just We are next to each other on the train, but Dutch often keeps the idea of posture more explicitly.

Naast elkaar means next to each other.

It is made up of:

• naast = next to / beside
• elkaar = each other

So literally it is something like beside each other.

This phrase is very common when two or more people or objects are side by side:

• De stoelen staan naast elkaar. = The chairs are next to each other.
• Wij lopen naast elkaar. = We are walking next to each other.

Elkaar is the Dutch reciprocal pronoun, meaning each other.

It is used when the relationship goes both ways:

• We helpen elkaar. = We help each other.
• Ze kennen elkaar. = They know each other.
• Wij zitten naast elkaar. = We are sitting next to each other.

Without elkaar, naast would need some other object:

• Wij zitten naast Jan. = We are sitting next to Jan.
• Wij zitten naast de deur. = We are sitting next to the door.

So elkaar is what gives the meaning each other.

In standard Dutch, you usually say in de trein because you are physically inside the train.

Compare:

• in de trein = in the train
• in de auto = in the car
• in het vliegtuig = in the airplane

But Dutch uses op for some means of transport where you are more thought of as being on them rather than enclosed by them:

• op de fiets = on the bicycle
• op de motor = on the motorcycle

English often says on the train, but Dutch normally says in de trein.

De trein means the train, while een trein means a train.

In this sentence, de trein usually refers to the specific train the speakers are in. Dutch often uses the definite article when the situation is clear from context.

So:

• Wij zitten naast elkaar in de trein. = We are sitting next to each other in the train / on the train we are in.
• Wij zitten naast elkaar in een trein. = We are sitting next to each other in a train (less specific, more like introducing the situation)

Both are grammatically possible, but de trein is the natural choice in most real situations.

Yes. That is completely normal and probably the most common spoken version.

Dutch subject pronouns often have:

• a stronger/full form: wij
• a weaker/common form: we

So these are both correct:

• Wij zitten naast elkaar in de trein.
• We zitten naast elkaar in de trein.

The meaning is the same. The difference is mostly style, emphasis, and rhythm.

Yes, Dutch word order is flexible, but the finite verb in a main clause normally stays in second position.

The neutral order here is:

• Wij = subject
• zitten = finite verb
• naast elkaar = adverbial phrase
• in de trein = prepositional phrase

So the standard sentence is:

• Wij zitten naast elkaar in de trein.

You can also move another element to the front for emphasis, but then the verb still stays second:

• Naast elkaar zitten wij in de trein.
• In de trein zitten wij naast elkaar.

These are grammatical, but they sound more marked or context-dependent. The original sentence is the most neutral.

Dutch often places more specific relationship/location information before a broader setting, but there is some flexibility.

Here:

• naast elkaar tells you how the two people are positioned relative to each other
• in de trein gives the broader location

So Wij zitten naast elkaar in de trein feels natural because it first says the relationship between the people, then the setting.

You could also say:

• Wij zitten in de trein naast elkaar.

That is also correct. The difference is mostly one of emphasis and rhythm, not basic meaning.

The infinitive is zitten.

Present tense:

• ik zit = I sit / am sitting
• jij zit = you sit / are sitting
• u zit = you sit / are sitting
• hij/zij/het zit = he/she/it sits / is sitting
• wij zitten = we sit / are sitting
• jullie zitten = you sit / are sitting
• zij zitten = they sit / are sitting

So wij zitten is the correct form for we.

Yes.

• naast elkaar = next to each other, side by side
• bij elkaar = together / with each other / near each other

So if you want to say that two people are specifically sitting side by side, naast elkaar is the right choice.

Examples:

• Wij zitten naast elkaar. = We are sitting next to each other.
• Wij zitten bij elkaar. = We are sitting together / near each other.

Bij elkaar is less precise about the exact position. You could be near each other without literally being side by side.

It is not the natural way to say this in ordinary Dutch.

A Dutch speaker strongly prefers zitten because the people are seated. Using zijn would sound unusual unless there were some very special context where posture was irrelevant and you were speaking in a more abstract way.

So for a learner, the best rule is:

• for people seated somewhere, use zitten
• for people standing somewhere, use staan
• for things lying somewhere, use liggen
• use zijn when no posture verb is appropriate

That is why Wij zitten naast elkaar in de trein is the idiomatic sentence.